Chapter 1 - Causes of diseases

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  • Created on: 03-11-15 19:57
What are microorganisms that cause disease called?
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What is disease?
A description of certain symptoms either physical or mental. A malfunction of the body or mind which has an adverse effect on good health
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What makes a microorganism a pathogen?
It must: gain entry to host and colonise tissues, resist defences of the host, cause damage to the tissues
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What is an infection?
Where pathogens gets into the host and colonises its tissues
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What happens after an infection?
Disease occurs which leads to recognisable symptoms in the host
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What is it called when a pathogen is spread from one individual to another?
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How does a pathogen enter the body?
By penetrating one of the organisms interfaces with the environment
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What is an interface?
Surface or boundary linking two systems (external to internal)
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What is an example of an interface?
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What is a pathogen? Examples
Bacteria, Virus, Fungi
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When does invasion of the skin occur?
When the skin is broken through cuts, grazes and bites
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Why is the skin an effective barrier to infection?
Forms a thick and continuous layer
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Give 2 examples of where interfaces have common points of entry
Gas exchange system, Digestive system
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List natural defences against the entry of pathogens
Mucous layer, enzymes, stomach acid
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How does a mucous layer protect exchange surfaces?
Forms a thick and sticky barrier that is difficult to penetrate
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How does the production of enzymes protect exchange surfaces?
Breaks down pathogens
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How does the production of stomach acid protect exchange surfaces?
Kills microorganisms
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What is a microorganism?
A single celled organism that is too small to be seen without a microscope
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Pathogens which enter the gas exchange system:
Influenza, TB, Bronchitis
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Pathogens which enter via the digestive system
Cholera, Typhoid, Dysentery
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How do pathogens cause disease?
By damaging host tissues and producing toxins
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Factors that can cause disease
Pathogens, Lifestyle, Genetics
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What does the cholera bacteria toxin lead to?
Excesive water loss from the lining of the intestines
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Give an example of a single cause disease
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How do pathogens damage host tissues?
Prevents tisues functioning properly, viruses inhibit the synthesis of DNA RNA and proteins, breaks dow cell membrane
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What causes the level of damage and the onset of symptoms?
How rapidly the cells divide
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Gastroenteritis pathogen:
Pathogens divide every 30 minutes, symptoms of vomiting and diarrhoea start within 24hrs, causes damage in large numbers
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When does the typhoid bacterium cause harm?
When their numbers are relatively small
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Why are oral antibiotics not used to treat gastroenteritis?
Vomiting and diarrhoea mean the antibiotic is unlikely to remain in the body long enough to be absorbed
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What is epidemiology?
Study of incidence and pattern of a disease to find ways of preventing and controlling it
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Analysing graphs and what to look for:
Patterns, differences between lines, overall correlation
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How do they collect data?
Looks for a relationship between the disease and factors
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What is a correlation?
When a change in one variable is reflected by a change in another variable
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What is the problem with a correlation?
Cannot determine a causal effect
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What shows a causal connection?
Experimental evidence to show the link
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Why should data be looked at critically?
To decide how reliable the data is
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How is data reliable?
Factor being measured? Were methods reliable? How was the data collected? Could there be experimenter bias? Has it been repeated? Have the same results been found?
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What is risk?
A measure of the probability that damage will occur as a result of a gien hazard
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What are the 2 concepts of risk?
The probability of occurring and the consequences of the event
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How can risk be measured?
Value which ranges from 0% to 100%
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Why do health risks need a timescale?
To state the risk over a period of time is more meaningful
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How is risk relative?
Comparing those with and without the hazard
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What do we need to know to understand risk?
Time, amounts, other factors, cultures
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Why can statistics be misleading?
They focus on a single figure
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What can our lifestyle expose us to?
Environmental and carcinogenic factors
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Specific lifestyle factors that lead to an increased chance of cancer
Smoking, diet, obesity, physical activity, sunlight
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What is the largest cause of death in the UK?
CHD Coronary Heart Disease
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Lifestyle factors contributing to CHD
Smoking, high blood pressure, blood cholestrol levels, obesity, diet, physical activity
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How to reduce the risks of CHD and cancer
Not smoking, avoid being overweight, reducing salt intake, reducin cholestrol and sat fat, regular aerobic exercise, low alcohol, increased fibre and antioxidants
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Why was there an increase in deaths from lung cancer around 1900?
Increase in smoking
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Why were we able to find a cause and effect between smoking and lung cancer?
Epidermiological evidence since 1951, statisitical facts about smokers
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Why was the smoking causal effect not seen as conincidential?
There was a very large sample size
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What other evidence was there except from statisitics?
1960's dog experiment where those who inhaled unfiltered smoke developed pulmonary disease and lung cance. This was compared to dogs who inhaled filteed smoke instead and had no side effects
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Further evidence against smoking
Found to contain carcinogens and Benzopyrene which mutate DNA by being absorbed by epithelial cells and these divide rapidly into a tumour
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What happened when the link between smoking and lung cancer was causal?
Reduced number of smokers, government raised taxes, banned adverts, placed public health warnings, banned in public places
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Other cards in this set

Card 2


What is disease?


A description of certain symptoms either physical or mental. A malfunction of the body or mind which has an adverse effect on good health

Card 3


What makes a microorganism a pathogen?


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Card 4


What is an infection?


Preview of the front of card 4

Card 5


What happens after an infection?


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